| Message ID | 833CE971-9EBB-4B41-8CFD-6DC6827FDE4C@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | Avoid unaligned fetch in ladr_match() | expand |
On Thu, 1 Feb 2024 at 18:11, Nick Briggs <nicholas.h.briggs@gmail.com> wrote: > > There is no guarantee that the PCNetState is allocated such that > csr[8] is allocated on an 8-byte boundary. Since not all hosts are > capable of unaligned fetches the 16-bit elements need to be fetched > individually to avoid a potential fault. Closes issue #2143 The way to mark that a commit fixes an issue is to have: Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2143 just above the Signed-off-by: line. > Signed-off-by: Nick Briggs <nicholas.h.briggs@gmail.com> > --- > hw/net/pcnet.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c > index 494eab8479..ad675ab29d 100644 > --- a/hw/net/pcnet.c > +++ b/hw/net/pcnet.c > @@ -632,7 +632,7 @@ static inline int ladr_match(PCNetState *s, const uint8_t *buf, int size) > { > struct qemu_ether_header *hdr = (void *)buf; > if ((*(hdr->ether_dhost)&0x01) && > - ((uint64_t *)&s->csr[8])[0] != 0LL) { > + (s->csr[8] | s->csr[9] | s->csr[10] | s->csr[11]) != 0) { > uint8_t ladr[8] = { > s->csr[8] & 0xff, s->csr[8] >> 8, > s->csr[9] & 0xff, s->csr[9] >> 8, Reviewed-by: Peter Maydell <peter.maydell@linaro.org> (The whole function feels kind of clunky, eg I have a feeling you could index directly into the csr[] arrays rather than constructing the ladr[] byte array, but this is the simple fix for the problem at hand.) thanks -- PMM
diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c index 494eab8479..ad675ab29d 100644 --- a/hw/net/pcnet.c +++ b/hw/net/pcnet.c @@ -632,7 +632,7 @@ static inline int ladr_match(PCNetState *s, const uint8_t *buf, int size) { struct qemu_ether_header *hdr = (void *)buf; if ((*(hdr->ether_dhost)&0x01) && - ((uint64_t *)&s->csr[8])[0] != 0LL) { + (s->csr[8] | s->csr[9] | s->csr[10] | s->csr[11]) != 0) { uint8_t ladr[8] = { s->csr[8] & 0xff, s->csr[8] >> 8, s->csr[9] & 0xff, s->csr[9] >> 8,
There is no guarantee that the PCNetState is allocated such that csr[8] is allocated on an 8-byte boundary. Since not all hosts are capable of unaligned fetches the 16-bit elements need to be fetched individually to avoid a potential fault. Closes issue #2143 Signed-off-by: Nick Briggs <nicholas.h.briggs@gmail.com> --- hw/net/pcnet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)